Pump



PUMP

8 Sheets-Sheet 1 Filed April 14, 1964 Oct. 18, 1966 BENNETT 3,279,382

PUMP

Filed April 14, 1964 8 Sheets-Sheet 2 Oct. 18, 1966 M. D. BENNETT PUMP 8Sheets-Sheet 5 Filed April 14, 1964 M. D. BENNETT Oct. 18, 1966 PUMP 8Sheets-Sheet 4 Filed April 14, 1964 8 Sheets-Sheet 5 Oct. 18, 1966 M. D.BENNETT PUMP Filed April 14, 1964 Oct. 18, 1966 M. D. BENNETT PUMP 8Sheets-Sheet 6 Filed April 14, 1964 Oct. 18, 1966 Filed April 14, 1964M. D. BENNETT PUMP 8 Sheets sheet 7 IJAI Oct. 18, 1966 M. D. BENNETTPUMP 8 Sheets-Sheet 8 Filed April 14, 1964 T MW1 Q Nkm INVENTOR. WALW/A/5 1701M @dh mme/vaif,

United States Patent 3,279,382 PUB [P This invention relates to pumpsand, more particularly, to pumps adapted for conveying buildingmaterials such as plaster, concrete, mortar, and like moist,compressible materials.

Machines for pumping building materials such as plaster, concrete,mortar, and the like have been developed and have been in use over along period of time. These building material pumps have been developedto transport these materials from one location to another as well as toallow the building materials to be applied by spraying. In theconstruction of a pumping unit for spraying the building materials, theimportant consideration is that the building material be delivered fromthe pump at a uniform spray rate to thereby allow the materials to beuniformly applied over a large area. These criteria, then, are differentthan when a machine is to be developed for the mere transportation ofthe building materials. One such machine adapted for applying buildingmaterials at a substantially uniform rate is disclosed in the divisionalapplication of Marvin D. Bennett et al., Serial No. 242,578, filedNovember 30, 1962, now Patent 3,172,363, and assigned to the sameassignee as the present application.

The use of any machine in a construction project is directed to thereduction of the building costs which can be attributed to labor costs.In a large construction project the economic feasibility of machines forhandling such building materials is not only readily apparent but to alarge extent necessary with present day construction techniques. Suchmachines include pumps for conveying these building materials from onelocation to another, conveyors, hoists, elevators, and machines forpreparing the building materials such as concrete mixers, cement mixers,and the like. In the very large construction projects in which a longperiod of time is required from breaking ground to the completion of theproject, it is economically feasible to set up this type of constructionequipment on a permanent basis, equipment generally not readilyportable, for the duration of the project. As a result, concrete pumps,for example, have been developed and have been used for a large numberof years for conveying concrete and other building materials from onelocation on the project to another location. Such concrete pumps arerepresented in Patents Nos. 2,448,104 and 2,685,259.

When these prior art pumping units are utilized for handling concrete,they have the capability of pumping concrete on the order of 6-100 cubicyards per hour through a pipeline which may have a diameter on the orderof six inches. These machines not only have to be permanently installed,but take a number of days to install and, once installed, require two tothree operators. It will be readily appreciated that on a small buildingproject, in the construction of commercial structures such as an ofi'icebuilding or apartment, the project normally does not require suchextensive construction equipment. Furthermore, on these smallerconstruction projects it has been common practice for the concrete to bedelivered to the job in a ready-mixed concrete truck so that theconcrete may be used or applied within a very short time of the arrivalof the ready-mixed concrete truck. These smaller construction projectscan be characterized from the amount of concrete required to be anywherefrom 12- 300 cubic yards of concrete per day. The ready-mixed truck, asis well known, consists of the adaptation of a motor vehicle or truckwith a concrete mixer to allow the 3,279,382 Patented Oct. 18, 1966concrete to be substantially mixed while in transport. The provision ofa pumping unit for conveying the concrete from such a ready-mixedconcrete truck to the desired location on the construction projectwould, of course, eliminate the requirement of manually transporting theconcrete from the concrete truck to the desired location on the project.In the past this conveyance has been in the form of manually wheelingthe concrete by means of a wheel barrow to a particular location for useor onto a conveyor or hoist for application at an elevated location.Since the type of construction projects under consideration are of alimited time duration, it should be appreciated that the portability ofany such pumping unit is an important feature since it allows thebuilding contractor to use the unit on different construction projectsand thereby maximize the productive time of the pumping unit. Theproduction time, of course, involves the time required for setting upthe machine from one project to another as well as the time required forcleaning out the machine. The time required for cleaning out a pump isan important consideration since in handling these moist, compressiblebuilding materials they do dry out and set in the machine, which mayrender the pump inoperable for the next project unless properly cleanedout.

Since these machines are specifically adapted for merely conveying thebuilding materials from one location to another, the application of thebuilding materials by means of the conduit is an important considerationnot only from a portability standpoint but also from the operatorsstandpoint. The ease of handling such a conduit dictates that alight-weight conduit be employed and, as a result, the conduit is moresusceptible to vibrations created by the pumping action. The pumpingunit must deliver the building material or concrete at a rate so as tominimize vibrations created by the pumping action. This is a necessitynot only from the operators standpoint of handling the conduit but alsofrom the standpoint of eliminating the movement of structural fonns overwhich the conduit is laid. The light-weight conduits necessarily impliesthat the diameter is reduced and, therefore, the rocks employed in theconcrete mix, for example, may have a tendency to pack within theconduit or hose itself. This packing may also result from the kinking ofthe conduit by the operator or wherein the conduit goes through twopoints of diflFerent elevations such as when the conduit is passed overa concrete form. In the prior art pumps, due to the power units that areemployed for the large capacity pumps, such as exemplified in theaforementioned patents, if packing occurs it may cause the pumpingaction to stop or cause even the jamming or breaking of some of theworking parts of the machine.

A consideration of the pumping action required for pumping the buildingmaterials under consideration from the standpoint of pumping concretewill reveal that the drive means for the pump must respond in a propermanner to the problems that develop in the pumping of various concretemixes to allow the problem to be alleviated without any breakage of thepump parts and within a minimum time. As is well known, concretecomprises a paste of sand and cement along with stones. The stones maybe graduated in size from one-quarter inch to one inch. The paste ofsand and cement is employed in the correct proportions to fill the voidsbetween the stones. In the pumping of mixtures of this type, it has beenfound that quite often the stone separates from the paste and theconcentration of stone becomes immovable to cause packing in the pump.The stones will be concentrated to such an extent that they will bridgeacross an opening in the pump proper or bind in the discharge conduit tostop the flow of material. This packing will occur during the priming ofthe pump as well as during the pumping operation. One of the reasons forthe separation of the stone and paste is due to the use of a mixturewherein the paste and stones are not in the proper proportions to form afluid mix for pumping purposes.

The separation of the paste and concrete can also result from the actionof the discharge valve of the pump. This separation occurs for examplewhen the pumping of the concrete from a hopper to the discharge outletis obstructed or due to the wearing of the discharge valve. The presentinvention provides an improved, simple, portable positive displacementpump for conveying building materials such as plaster, concrete, mortar,and like moist, compressible materials that is readily adaptable forsmall construction projects. In one particular embodiment of theinvention the pump is adapted to be mounted on the chassis of amotorvehicle or truck and to be powered from the power unit of thetruck. This construction not only results in a one-piece mobile unit forease of movement from one location to another but also for travel on ahighway. .This integral construction eliminates the requirement for theprovision of a separate power unit for the pump.

When the pumping unit of the present invention is employed for pumpingconcrete, it is capable of pumping concrete having a one-inch rock mixat a rate of 50 cubic yards per hour and which volume may be controlledby means of a volume control from -50 cubic yards per hour. In addition,the pump may be remotely controlled so that the operator can control thetotal volume of concrete delivered and the response of the pump is suchthat essentially a very small volume, a handful, will be delivered.

From a structural standpoint, the pump of the present inventioncomprises a pair of pumping units in combination with a single, wearresistant valve for controlling the discharge of the materials and underthe control of a fluid power control circuit. The control of the pumpingunits is to cause them to operate in alternate sequences and to shiftthe single control valve at a point in the pumping sequences when thepumping units are both momentarily at rest and, therefore, no materialis being moved through the control valve to thereby prevent theseparation of the paste and stones and the material packing at thecontrol valve. The pumping units may comprise piston-cylinder pumpingassemblies that are controlled so that the control valve is shifted whenone of the pistons is at the end of its pumping stroke and while theother piston is at the end of its return stroke. With the operation ofthe pumping units after the shift in the position of the control valve,the material being pumped is provided with an unobstructed, full flowpath from the hopper to one of the pumping units and from the otherpumping unit through the discharge outlet. This pumping action providesan almost steady How of material and with a minimum of pulsations. Thefluid power control circuit is adapted to maintain a safe pressure onthe pump in the event packing occurs during the operation of the pump,thereby eliminating the danger of bursting the discharge conduit. T 0this same end, the pumping action can be reversed to relieve thepressure in the system when packing has occurred. The reversing actionalso allows the material in the discharge conduit to be emptied uponcompletion of a project.

The simplified construction of the pump allows ready access to the workpistons of the pump whereby the pumping unit may be cleaned inapproximately ten minutes.

These and other features of the present invention may be more fullyappreciated when considered in the light of the following specificationand drawings, in which:

FIG. 1 is a perspective view of a concrete pump mounted on a motorvehicle embodying the invention and illustrated pumping concrete; 7

FIG. 2 is an exploded view, with parts broken away, of the concrete pumpof FIG. 1;

FIGS. 3-6 are schematic representations of the fluid control circuit forthe concrete pump of FIGS. 1 and 2,

showing portions of the pump in section, and with the circuitrepresented in its different phases of operation;

FIG. 7 is a partial top view, with portions broken away, of the controlunit end of the pump; and

FIG. 8 is a diagrammatic representation of the power assembly for thefluid pressure generator of the pump including a schematicrepresentation of the electrical controls for the pump;

The pump of the present invention is particularly adapted for pumpingmoist, compressible materials such as the building materials, plaster,concrete, mortar, and the like. In order to simplify the description ofthe invention, the pump will be described in conjunction with thepumping of concrete.

The concrete pump 10 of the present invention is mounted to the rear ofthe cab of a, motor vehicle or truck 11, see FIGS. 1 and 2. The motorvehicle 11 is provided with a conventional power unit located to thefront of the cab of the motor vehicle and beneath the hood 12 in theconventional fashion. The power unit for the motor vehicle 11 is alsoemployed as the primary power source for the concrete pump 10 and istherefore provided with a drive member (not shown) coupled between thepower unit for the motor vehicle 11 and the concrete pump 10. It will,of course, be appreciated that the power unit for the motor vehicle maybe any type of unit such as a conventional internal combustion enginewhich may be in the form of a diesel engine or a gasoline engine. Thepower unit may be any other type of convenient unit when the pump is notmounted on a motor vehicle, such as an electric motor, for example. Theconcrete pump 10 can be remotely controlled from an individual controlpanel 13 mounted on one side of the vehicle and behind the cab thereof.

The concrete pump generally comprises a pair of pumping units 14 and 15mounted on opposite sides of a hopper 16. The hopper 16, as isconventional, is utilized to receive and store the material or concreteto be pumped and supplied thereto. The concrete may be supplied by aready-mix concrete truck, a portion of the chute being illustrated inFIG. 1 in operative relationship with the hopper 16.

The motor vehicle 11 is also provided with a walk-way 17 arrangedadjacent each of the pumping units 14 and 15 to allow the pump operatorto control the discharge of the concrete into the hopper 16, forexample.

The pumping units 14 and 15 are connected with a control valve unit 18defining a common concrete chamber 21 for the pumps 14 and 15 and beingarranged in communication therewith and with the hopper 16 to allow thepumping units to be directly charged with con crete to be pumped fromthe hopper 16 by means of the unobstructed flow path provided by thechamber and to be discharged in response to the pumping action through acommon outlet 19 and then through a conduit 20 to the point ofutilization of the concrete. The control valve unit 18.is provided witha single control valve 21 that is adapted to assume two positions andthereby subdivides the chamber 21 into two portions allowing thealternate charging and discharging of the concrete to occursubstantially simultaneously in each portion.

The positions of the control valve 21 are effective for substantiallyclosing ofi one of the pumping units from the hopper 16 while allowingthis same pumping unit to discharge concrete through the outlet 19.During this same interval the other pumping unit is substantially closedoff from the discharge outlet 19 while being in communication with thehopper 16 through the hopper port 16 The charging of a pumping unitresults due to the drawing in of the concrete from the hopper 16 due tothe suction created by the pumping unit to be charged. As illustrated inFIG. 2, the control valve 21 is positioned by its fluid pressure motor22, illustrated in the form of a hydraulically operated piston-cylinderunit, in a position to allow the pumping unit 14 to discharge concretethrough the discharge outlet 19 while the pumping unit is drawingconcrete from the hopper 16. A conduit is coupled to the dischargeoutlet 19 and may be a rigid pipe or a flexible conduit such as thethree-inch rubber hose shown in FIG. 1.

The pumping units 14 and 15 may also be constructed in the form of fluidpressure pumping units and preferably are hydraulically operatedpiston-cylinder units whereby the units are charged during their returnstrokes. The pumping units 14 and 15 and the fluid pressure motor 22 arecontrolled by a fluid power control circuit, preferably a hydrauliccircuit, adapted to control the alternate charging and discharging ofthe concrete into and out of the pumping units 14 and 15 whilecontrolling the fluid motor 22 to position the control valve 21 duringan interval both of the pumping units 14 and 15 are at rest to allow theconcrete to be discharged through the discharge outlet 19 and a conduit20 with a minimum of pulsations.

As will become more readily apparent hereinafter in conjunction with thedescription of the fluid power control circuit, the action of thecontrol valve 21 with respect to extraordinarily large pieces of stonethat may have been combined with the concrete mix or any foreign objectthat is conveyed into the common concrete chamber 21 will either besheared off or cut off as a result of the action of the control valve 21or, if the object is too hard to be cut off, the movement of the controlvalve will be stopped by the object without any damage to the pump 10,conduit 20, or operating and construction personnel.

Now referring to FIG. 3 the fluid power control circuit will bedescribed. The control circuit is a hydraulic circuit and is illustratedin FIG. 3 in its off or de-energized position. The fluid pressure forthe control circuit is generated by a fluid pressure generator 30,schematically illustrated as a combination pump and volume governor.This pressure generator combination may be in the form of a commerciallyavailable variable volume pump in combination with a volume governorsuch as the Model MR pump and MGP governor manufactured by RacineHydraulics & Machinery, Inc., Mobile Division, of Racine, Wisc. Thegovernor functions to maintain a constant flow regardless of pumppressure change or pump shaft speed change. The action of the pump unitfunctions to build up a pressure in the associated hydraulic controlcircuits up to 1,000 pounds and then stops pumping, maintaining the1,000 pounds pressure throughout the system without pumping any fluid,oil in this instance. The pressure may be maintained throughout thecontrol circuit for an indefinite period of time since there is no heatbeing generated in the system.

The illustrated fluid pressure generator 30 includes an orifice samplingport 31, a drain port 32, and a sampling port 33 for the governor and afluid or oil port 34 for the pump. The pump generates a pressure on theorder of 60 pounds per square inch at the fluid port 34. The fluid port34 for the pump maintains pressure on the associated pilot lines tomaintain a balanced 60 pounds per square inch on the lines connected tothe fluid line 41 at all times. The orifice sampling port 31 isconnected by means of an orifice sampling conduit 35 to one end of acheck valve 36. The drain port 32 of the governor is, in turn, connecteddirectly to the fluid tank or oil tank 38 mounted on the motor vehicle11 behind the cab of the vehicle 11. The drain port 32 is connected tothe tank '38 by means of a conduit 37 and is diagrammaticallyrepresented as being connected to a sump. The sampling port 33 is inturn connected by means of a sampling line 39 to the junction 39 andwhich junction is directly connected to one of the ports of a pilotvalve 40 and the other junction is connected to a fluid line 41 havingits other end directly connected to the fluid port 34 of the pump of thegenerator 30.

The pilot valve 40 is a solenoid operated valve and is operated by meansof the solenoid 42, which is connected to a direct current source ofpotential shown as the vehicle battery 43 provided with an on-olf switch44. The

o'n-olf switch 44 is located on the pump control panel 13 of the motorvehicle 11. The pilot valve 40 is a reversible valve and is shown in itsoff position with its pressure port P directly connected by means of theconduit 39 to the junction 39 and in communication with the A port. Theport A of pilot valve 40 is always blocked. The T port, or the tankport, is directly connected to the tank 38 by means of the conduit 45.The conduit 45 is, therefore, connected through the port T and the portB of the pilot valve 40 in communication therewith and by means of thepilot conduit 46 to a hydraulic motor 47 provided for operating a volumecontrol valve 48. The volume control valve 48 is shown in its offposition whereby the oil in the line 41 is not conveyed through thevalve 48 to its exit port and the oil line 49 connected thereto. Thevolume control valve 48 is further provided with a manual volume controlknob 50 for controlling the volume of the fluid passing through thevalve 48 when it has been operated to its open position by the hydraulicmotor 47. Operation 'of the hydraulic motor 47 opens the volume controlvalve 48 to a preselected position and when open may then be varied bymeans of the volume control knob 50, which is also ldcated on the pumpcontrol panel 13.

The check valve 36 is connected in serial fashion relationship withanother check valve 51 by means of the conduit 52 and the junction 46for the conduit 46. The opposite side of the check valve 51 is providedwith a conduit 53 which is directly connected to a relief fluid line 54connected to the entry port of a relief valve 55. The check valve '36 isarranged to be in an open position only when the pressure in the orificesampling line 35 is greater than the pressure in the conduit 52, such aswhen the control circuit is in the illustrated off position. In the samefashion, the check valve 51 is illustrated in FIG. 3 closed and isopened in response to the greater pressure being applied at the junction46 side of the valve. The relief valve 55, as illustrated, is normallyin a closed position to the flow of fluid and has its exit portconnected by means of a conduit 56 to the tank 33.

The fluid conduit 49 is connected to the exit port of the volume controlvalve 48 and has its opposite end connected to the pressure port P of afour-Way reversing valve 57. The reversing valve 57 is normally arrangedWith the ports P and A in communication. The port A is connected to afluid line 53 which has its opposite end directly coupled to the pumpingunit 14 for pressurizing the unit. Similarly, fluid conduit 59 isconnected to the B port of reversing valve 57 for pressurizing thepumping unit 15. The port B of the four-way reversing valve 57 in itsnormal position is in direct communication with the T port or the tankport of this valve. The T port, in turn, is connected by means of aconduit 60 draining into the tank 38. The four-way reversing valve 57 isoperated by a pair of sequencing valves 61 and 62 for sensing thepressure in the cylinder 22 on the opposite sides of the piston 22 ofthe fluid motor 22. The sequencing valves 61 and 62 are provided withindividual check valves 63 and 64 respectively to allow the free flow ofoil from the reversing valve 57. The check valve 63 is connected betweenthe inlet of the sequencing valve 61 and to receive and pass oil fromthe reversing valve 57. The check valve 64 is connected between theinlet of the sequencing valve 62 and to receive and pass oil from theopposite end of the reversing valve 57 from the check valve 63. Thecheck valve '63 opens to pass the oil from the reversing valve 57 whenit is operated by the sequencing valve 62 and the check valve 64 opensin response to the operation of the valve 57 by the sequencing valve 61.

The fluid port 34 of the pressure generator 30 is also connected bymeans of a T connection for the fluid line 41 to a conduit 73 having itsopposite end connected to a port for an accumulator 74. The accumulator74 is provided with a check valve to prevent the back flow of oil fromthe accumulator proper which is charged at 200 pounds per square inch.When the system pressure ex ceeds the 200 pound pressure, the associatedcheck valve opens up, admitting oil into the accumulator proper. Theremaining port of the accumulator 74 is connected by a fluid line 75 toa port 76 for a pilot valve 77 mounted integral With the pumping unit14. This same fluid conduit 75 is connected to a corresponding integralpilot valve 78 for the pumping unit 15. The port 79 for the pilot valve78 is connected to a conduit 80 and a T connection to the fluid conduit75.

The pumping units 14 and 15 may be of any convenient construction andthe preferred construction in accordance with the present invention isto provide reciprocating piston-cylinder assemblies whereby the forwardor power stroke of the pistons is utilized for pumping the chargedconcrete through the concrete chamber 21 and the discharge outlet 19 andthe return stroke is utilized to charge concrete into the cylinder unitsfrom the hopper 16 through the concrete chamber 21 The construction ofthe pumping units 14 and 15 is essentially identical and only one of theunits need be examined. The pumping unit 14 is illustrated in FIG. 3with its piston 14 at its left hand extremity or at the end of itsreverse stroke. The hollow piston 14 is provided with a piston head 14mounted for sliding movement within the cylinder section 14. Thecylinder section 14 of the pumping unit 14 is one of the three cylindersections for the pumping unit 14. Another cylinder section is identifiedas the section 14d and is mounted in a coaxial relationship with thethird cylinder section 14 The cylinder section 14 is mounted between andcoaxial with the sections 14 and 14 The cylinder section 14 sli-da blyreceives the rear portion of the piston 14 mounting the head 14.

The cylinder portion 14 and the corresponding cylinder portion 15 forthe pumping unit 15 are each provided with means for cooling the pistons14 and 15 respectively. As specifically shown, these pistons are adaptedto be supplied with a heat exchange fluid for jacketing each of thepistons 14 and 15 The heat exchange fluid may be water supplied by awater conduit 82 connected between suitable ports for the cylindersections 14 and 15 and a water line 83 connected to a water tank 84carried by the motor vehicle 11 directly behind the cab of the vehicleand adjacent the oil tank 38, see FIGS. 1 and 2.

The provision of the means for the cooling of the pistons 14 and 15 isan important, practical aspect of the present invention since it notonly functions to cool these pistons on every piston stroke, but alsoserves as a lubrieating medium for the back sides of the pistons toextend the life of the pistons. The movement of the piston 14 into thehydraulic fluid carrying piston sections 14 and 14 also produces a heatexchanging action with the hydraulic fluid of the system. It wil also berecognized that the heat that is generated by the operation of thepumping units 14 and 15 can cause the concrete that is charged or drawninto the cylinder sections 14 and 15 from the hopper 16 to heat up andset. The setting of any substantial amount of concrete in the cylindersections 14 and 15 would, of course, render the pump inoperative. Withthe water occupying the volume between the piston 14 and the cylindersection 14", for example, it prevents air from being drawn into thepiston units. It should also be noted that, as illustrated in FIG. 3,the water has been substantially removed from the cylinder section 14since the associated piston 14 is at the end of its return stroke. Intraveling to this end position, the piston head 14 pressurizes the waterin the section 14 forcing it through the conduit 82 and into either theWater tank 84 or into the cylinder unit for the pumping unit 15 or both.In the same fashion, when the piston 15 begin its return stroke, thewater is fed back from the cylinder section 15 to the cylinder section14. The water supply in these cylinder sections is maintained at apreselected level as a result of the conduit 82 being connected to thewater tank 84.

Another important aspect of the present invention is the construction ofthe pumping units 14 and 15 and, more particularly, the construction ofthe piston-cylinder units integral with their individual pilot valves 77and 78. This construction simplifies the over-all hydraulic controlcircuit. The pilot valve 77 is removably mounted to the rear end of thecylinder portion 14 as illustrated in FIG. 3. The pilot valve 77 is atwo-position valve and is provided with three ports. The port 7 6, asmentioned hereinabove, is connected by means of the conduit 75 to theaccumulator 74. The pilot valve 77 is provided with a port definedadjacent the port 76 and shown connected to the tank 38 by means of thefluid conduit 86. The third port is identified as the port 87 and isconnected by means of a fluid conduit 88 to the conduit 66. The pilotvalve 77 has the port 76 closed, while the ports 85 and 87 areinternally connected thereby coupling the conduits 86 and 88. Thisposition of the pilot valve 77 corresponds to the left-hand position ofthe piston 14, as shown. The pilot valve 77 is operated by means of apilot rod 89 slidably mounted to the piston head 14 and to be movedthereby. The pilot rod 89 is provided with a stop 89 adjacent itsforward end and .a similar stop 89 adjacent its rear end. The coactionof the pilot rod 89 and piston 14 is such that the piston slides alongthe rod 89 until the piston head 14 engages the stop 89 or 89 at whichtime the piston head 14 carries the pilot rod 89 along with it to changethe position of the pilot valve 77. The other positions of the pilotvalves 77 and 78 can now be appreciated by examining the valve 78, sincethe piston 15*- is shown at the end of its pumping stroke. At this timethe port 79 and the port 91 for the pilot valve 78 are interconnected,while the remaining port 92 is maintained in a closed position. Theseports correspond to the ports 76 and 87 for the pilot valve 77 and arein communication when the valve 77 assumes its other position.

Piston head 14 is maintained in a sealed, sliding relationship with theinner wall of the cylinder portion 14 to prevent the fluid or oil topass therebetween. A chamber 14 is defined between the piston head 14and a sealing element 14 sealing the chamber 14 from the open end of thecylinder section 14 the end opening into the cylinder section 14. Thecylinder section 14 is provided with a port 14 communicating with thechamber 14 and illustrated with a fluid line 94 connected to thecorresponding port for the pumping unit 15. This port is illustrated asthe port 15 communicating with the chamber 15 whereby the fluid in thecylinder section 14, for example, may be transmitted through the chamber14 and the conduit 94 into the chamber 15 for the pumping unit 15. Theconduit 94 is also connected to the fluid conduit 54 having its oppositeend directly connected to the relief valve 55. It should be appreciatedthat the feeding of the fluid from one cylinder unit to the othercylinder unit in this fashion is effective to drive the correspondingpiston into its return stroke in response to the driving of the otherpiston into its pumping stroke. The fluid is continuously supplied tothe chambers 14 and 15 through the fluid path provided from the fluidgenerator port 34, fluid line 41, pilot lines 39 and 39 thecommunicating ports P and B of the pilot valve 40, through the opencheck valve 51, pilot line 53 including orifice 25, line 54 and line 94.The fluid line 54 is connected to the relief valve 55 to pass oil in thereverse direction when the pressure generated opens the relief valve.

The reversing valve 67 is provided to reverse the action of the fluidcontrol motor 22 and thereby reverse the action of the control valve 21.The operation of the reversing valve 67 is such that in the normal ordischarging position the concrete is discharged through the outlet 19and the conduit 20 while, when it is operated to the reversing position,it causes the concrete to be drawn back through the conduit 25) and theoutlet 19 and back into the hopper 16. The importance of this reversingaction can best be appreciated when it is considered that in pumpingconcrete any appreciable distance and, in partic ular, when the conduitis to pump concrete to an elevated location that with the completion ofthe work the conduit may be fully loaded with concrete. A fully loadedconduit is not only diflicult to handle but increases the difliculty andtime for dismantling and cleaning the .pump in preparation for itsreuse. With the provision of the reversing valve 67, the concrete can besimply drawn out of the conduit 20 and the concrete chamber 21 into thehopper 16 to facilitate cleaning the pump.

The reversing valve 67 is a manually controlled valve and is controlledthrough the push rod 100 which is accessible to the pump operatoradjacent the control panel 13, as best seen in FIG. 2. In its normalposition, of course, the valve 67 is arranged to pump concrete throughthe outlet 19 and for this operation a pair of ports are directlyconnected to the fluid lines 66 and 68 with the line 68 being alsoconnected to the left-hand end of the cylinder 22'. In the same fashion,the other pair of ports of the reversing valve 67 are connected betweenthe fluid lines 71 and 72, with the latter line being connected to theright-hand end of the cylinder 22 The reversing action results when thepush rod 1% is operated to move the valve sleeve to place the reversingports in position for interconnecting the fluid line 71 with the line 68while the fluid line 66 is interconnected with the fluid line 72. Itshould now be appreciated that this merely pressurizes and exhausts theopposite sides of the piston 22 from the normal pumping position of thevalve and thereby reverses the position of the control valve 21.

The fluid pressure motor 22, which operates the control valve 20, asmentioned hereinabove, is a piston-cylinder unit in which the piston 22reciprocates within the cylinder 22 in response to pressure beingapplied to the opposite sides of the piston 22. The fluid pressure motor22 is secured to the frame of the concrete pump and has its piston rod22 pivotally connected for operating the control member 21 by means of apivot arm 191 connected to the free end of the rod 22 and the centralpivotable shaft 21 of the valve 21. The rod 22 is located under theconcrete chamber 21. The control element 21, which is commonly referredto as a flapper valve, is pivotally mounted to the control valve unit 18by having its shaft 21 journaled -at its ends at the opposite faces ofthe control valve unit 18, 313 best seen in FIG. 2. The control valve 21is defined to be swingable within the common concrete chamber 21 toalternately substantially close off the discharge outlet 19 from one ofthe pumping units 14 and 15 while substantially closing off thedischarge outlet 16 of the hopper 16 from the other pumping unit. Stateddifferently, during the work or pressure stroke of one of the pumpingunits the concrete is discharged through the discharge outlet 19 due tothe position of the control or flapper element 21 while at this sametime the suction created by the return stroke of the other pumping unitis effective to draw the concrete from the hopper 16 and into the workportion of said other pumping unit.

The position of the control valve 21, as illustrated in FIG. 3, is theposition it assumes when the right-hand end of the fluid motor 22 ispressurized through the conduit 72 during the normal position of thereversing valve 67. It will now be appreciated that in this position thedischarge outlet 19 is substantially closed off from the pumping unit 15and, in particular, the cylinder section 15 while allowingcommunication, in fact defining an unobstructed, free flow path, betweenthe cylinder section 15 and the hopper 16 through the hopper oulet port16. At this same interval the hopper outlet port 16a is substantiallyclosed to the cylinder unit 14 while forming a direct free flow path forthe concrete to be discharged through the concrete chamber 21 and theoutlet 19. Upon the operation of the fluid pressure motor 22, theopposite side or the left-hand end of the piston 22 is pressurized tocause the control valve element 21 to 10 rotate in a clockwise directionto thereby close off the hopper discharge outlet 16 from the pumpingunit 15 while providing a direct concrete path between the cylindersection 15 and the discharge outlet 19. This action occurs since thepiston 22 has traveled to the opposite end or the right-hand end of thecylinder 22 thereby extending the piston rod 22 further towards thedischarge outlet 19 to cause the control element 21 to rotate or flip inthe clockwise direction about its shaft 21*, as can be betterappreciated from examining FIG. 6. Of course, at this same time thecylinder section 14 may be charged from the hopper 16 since the hopperoutlet port 16 is in direct communication therewith. This is the normalpivotal action of the control element 21 for discharging concrete and itshould be appreciated that with the actuation of the reversing valve 67the action is essentially the same except that with the pressurizing ofthe piston 22 in the opposite directions the pumping units 14 and 15 areadapted to draw the concrete from the conduit 20 through the dischargeoutlet 19 and into the cylinder sections 14 and 15 during the returnstroke of the corresponding pistons. During the interval that theconcrete is being drawn in from the discharge conduit 20, any concretein the common chamber 21 that is subjected to the pressure stroke of theother pumping unit will be forced into the hopper 16 through the hopperport 16.

The construction of the control element 21, as best seen from anexamination of FIG. 2, is defined as solid metal lic element that isWear resistant to the abrasive materials being pumped and of sufiicientstructural rigidity so that, if a stone or foreign object is conveyedinto the chamber 21 and between an end of the control element 21 and anadjacent side wall defining the concrete chamber 21, the stone will besheared off to allow the control element to continue its travel or, ifthe stone or foreign object is of a size whereby the power imparted tothe control element 21 is not sufficient to shear off this object, thecontrol element will be arrested against the object without stopping thepump 10. The stoppage of the control element 21 under these conditionsis an important advantage since it prevents the destruction or breakageof the pump elements that may occur when a mechanical drive system isresorted to.

To provide this stone cutting action the outer face of the memberdefining the discharge outlet 16 is provided with a radius having acenterline coincident with the centerline of control valve shaft 21'whereby the outer end of the control valve 21 sweeps by this face, asbest seen in FIG. 7. In the same fashion, the coacting surface for theopposite end of the control element 21 or the inner face of thedischarge outlet 19 is defined with a radius. The hopper dischargeoutlet 16 and the crosssection of the discharge outlet 19 are defined ofa shape to cause any large stones or foreign objects to be guided andpositioned along the aforementioned arcuate surfaces to cause only asingle stone to be positioned between an end of the control element 21and one of the discharge outlets. To this end, examining the hopperdischarge outlet 16, it will be seen that the opening is based on asquare with a pair of corners cut off, the top and bottom corners, andwith the remaining pair cut off and provided with a radius, see FIG. 2.It should be appreciated that a stone wedged between an end of thecontrol element 21 and the discharge outlet 16 will be pushed along theedge thereof to the top of the opening and then cut off by the continuedswinging action of the valve 21. Of course, the valve 21 will be stoppedif the stone is too large to be cut.

The control valve unit 18 is further defined as a unitary structurewhereby if the single control valve 21 is dam-' aged or renderedinoperative, the entire control valve unit may be readily replaced byanother unit through the removal of the four bolts, similar to the bolt102 securing the unit to the pump frame, as best seen in FIG. 2.

Another important feature of the present invention from the standpointof cleaning the pump is that the cylinder sections 14 and 15 areconnected with individual elbow members 103 and 104 removably connectedbe tween these cylinder sections and the structure of the control valveunit 18 defining the concrete chamber 21 as best seen in FIG. 7. Theelbows 103 and 104 are slipped into position between the control unit 18and their respective pumping units 14 and 15 and are maintained in thisposition solely due to the pressure provided by locking the respectiveclamping members 98 and 99. The clamping members 98 and 99 each have oneend pivotally connected to the pump frame and are placed in a lockingposition by means of a clamp handle such as the handle 98 illustratedfor the clamping member 98. It should be appreciated that opening thehandle 98 unclamps the elbow member 104 allowing it to drop to theground, thereby rendering the pumping unit 15 and the concrete chamber21 accessible to an operator. With the removal of one elbow member 103or 104, it should be appreciated that access to the associated pumpingpiston is afforded as well as access to the control valve element 21 andthe remaining portions of the concrete chamber 21 This can be bestappreciated from the broken away section of the elbow 104 illustrated inFIG. 2. With access to the interior of the work portion of the cylinderunits and the common concrete chamber 21 any necessary repairs may bereadily accomplished or any concrete that may have dried within thisarea can be readily scraped out and the entire pumping unit cleaned.

The discharge outlet 19 is adapted to accept a discharge nozzle 105 thatis clamped to the outer end of the discharge outlet 19 by means of theself-locking, clamping member 106, :the clamping member 106 being of substantially circular configuration while the other end of the dischargeoutlet 19 as well as the enlarged end of the discharge nozzle 105 aredefined with a groove around the outer periphery for snapping these twoelements together and accepting and securing the clamp 106 therein, thenozzle 105 being locked to the discharge outlet 19 when the clampingelement 106 is locked thereto. In the same fashion, the dischargeconduit may be locked to the discharge end of the nozzle 105 by beingclamped to the discharge end thereof, as best seen in FIG. 1. Thedischarge conduit is preferably in the form of a lightweight conduit toallow it to be readily handled by an operator and of sufficientstructural rigidity consistent with the abrasive nature of the concreteor building material being pumped. The pump of the present invention hasbeen successfully operated for pumping concrete employing a three inchrubber hose. It should also be understood that a rigid conduit or ironpipe may be employed as well as a flexible conduit. The concrete pump 10is capable of pumping a concrete mixture having one inch rock therein.It will also be appreciated, in view of the above description, that theconduit 20 may be readily disconnected from the nozzle 105 since, withthe machine at rest and the hydraulic control circuit turned off, thereis no pressure on the system and, therefore, the hose 20 can be readilydisconnected.

Now referring to FIG. 8, the means for coupling a power unit to thefluid pressure generator and the control means therefor will now bedescribed. The power unit, as mentioned hereinabove, may be anyconvenient power unit and is illustrated in FIG. 8 as comprising theinternal combustion engine of the motor vehicle or truck 11. The powerunit is identified by the reference numeral 120 and is a conventionalgasoline operated internal combustion engine illustrated with itscarburetor mounted thereon. The conventional drive shaft for the powerunit 120 is coupled to a power take-off unit 121 which has its oppositeend coupled to drive the fluid pressure generator 30 and, moreparticularly, the pump unit therefor. The power take-oft unit 121 is acommercially available unit and is mounted in accordance with thepresent invention in the cab of the motor vehicle adjacent the driversseat to be accessible to the operator. The power take-off unit 121 isswitchable by means of the switching arm 122 to couple the power unitdirectly to the motor vehicle for powering it and to decouple thepressure generator 30. Also, upon rotation of the handle 122, the powerunit 120 is decoupled for driving from the motor vehicle 11 and coupleddirectly to the pump 10 of the fluid pressure generator 30 for drivingsame. It will be understood that the coupling means or shaft between thepower unit 120 and the power take-01f unit 121 and also between the unit121 and the pump of the fluid pressure generator 30 are all ofconventional construction.

As mentioned hereinabove, the pilot valve 40 is controlled by a solenoid42 which is energized from the mot r vehicle battery 43. The solenoid 42is energized and tie-energized by means of a manually operated startstopswitch 44 located on the control panel 13. In addition to the solenoid42, there is provided a control solenoid 123 connected through thestart-stop switch 44 in parallel cincuit relationship with the solenoid42 for controlling and setting the speed of the power unit 120 duringthe pumping operation and, more particularly, for setting the enginespeed to a preselected speed upon the closing of the switch 44 forstarting the pumping unit '10. To this end, the solenoid 123 isconnected by means of a lead wire 124, which has its opposite endsconnected to the solenoids 42 and 123 and is also connected to theswitch 44 whereby both solenoids are energized upon closing the switch44. The other terminals of the solenoids 42 and 123 are each connectedto ground as is the remaining terminal of the battery 43. As isconventional, the solenoid 126 is provided with a plunger 123 which, inthis instance, mounts a bell crank 125. One end of the bell crank 125,the end identified by the reference numeral 125*, is coupled to thethrottle control of the carburetor of the power unit 120 to control thevolume of fuel supplied to the power unit and thereby the engine speed.With this arrangement, the energization of the solenoid 123 pulls itsplunger into a preselected location and thereby causes the bell crank125 to pivot in a counter-clockwise fashion to actuate the throttlecontrol. The bell crank 1 25 is maintained in this position as long asthe solenoid 123 is energized. This, then, effectively sets the powerunit 120 to a preselected engine speed during the intervals that thesolenoid 1-23 is energized. It will, of course, be appreciated that whenthe pump 10 is shut olT by opening the switch 44 not only is thesolenoid 42 de-energized, but the solenoid 123 is de-energized and thebell crank 125 rot-ates in a clockwise direction to thereby reset thepower unit 1-20 to its idling speed.

The pump 10 of the present invention is further arranged with controlmeans that allows the pump to be remotely turned on and off as well ascontrolling the engine speed remotely. For this pun-pose a control cable126 is connected with the vehicle battery 43 by means of a controlconductor 126 that is directly connected with the remote start-stopswitch 127. The normally open terminal of the switch 127 is connected toa relay coil 128 by means of a control conductor 126 The relay coil 128has its opposite end connected to ground potential to complete thecircuit to the battery 43. The relay coil 128 is provided with a pair ofnormally open contacts 128 and 128*. The contact 128 is connected to thenegative terminal of the battery 43, while the contact 128 is connectedin common with the normally open contact of the on-olf switch 44 tothereby place these pair of contacts in parallel circuit relationshipwith the switch 44. It should now be appreciated that with the on-offswitch 44 in .an open position the pump 10 may be turned on and off at aremote location by the operation of the switch 127 which actuates therelay 13 coil 128 and, in turn, closing the contacts 128 and 128 forsupplying current to the solenoids 4-2 and 123 simultaneously.

In addition to the remote control of the energization of the pump 10,the engine speed may be remotely controlled by means of a control cable130 having a control knob 131 connected at one end thereof for operatingsame. The free end of the control cable 130 is connected to the bellcrank 125 at the end identified by the reference numeral 125 or the endopposite from the end 125 The control cable 130 is of conventionalconstruction and is preferably a flexible cable which is effective tooperate the bell crank 125 to rotate it in a counter-clockwise directionupon operation of the control knob 131. It should now be appreciatedthat the actuation of the control knob 131 functions to change theengine speed from its preselected speed in accordance with the clockwiseor counter-clockwise rotation of the bell crank 125 as operated by thecable 130. For the remote control of the engine, it should beappreciated that such a speed control is an important practical aspectsince in the conventional internal combustion engines no governors areprovided and when the engine load is reduced some control is necessaryto prevent the engine from running away. With. such a remote controlarrangement, the operator of the pump may be located some distance fromthe pump and, in fact, may be controlling the discharge of the concretefrom the conduit 20 as is the operator illustrated in FIG. 1. With thisremote control arrangement the amount of concrete delivered at anyparticular location can be carefully controlled by the operation of theon-otf switch 127 and the response of the pump 10 is such that not onlylarge volumes of concrete may be controlled by small volumes down to andincluding a handful may be discharged by operating the remote switch 127on and off. This alleviates the necessity of communication between anoperator located at the control panel 13 and an operator at the point ofdischarge of the concrete.

Now referring to FIGS. 3 through 6, the operation of the fluid pressurecircuit controlling the pumping action will be described. The hydrauliccircuit is shown in FIG. 3 at its at rest position or ofi position, noconcrete is being pumped. It will also be assumed that the reversingvalve 67 is positioned in its normal concrete pumping position. With thehydraulic circuit in the off position, the fluid pressure generator 30provide fluid pressure at its pump fluid outletport 34 of 60 pounds persquare inch. This fluid or oil is coupled to the volume control valve 48by means of the line 41 but is not conveyed through the valve 48 due tothe valve 48 being in its off position. Thisfluid is also conveyed tothe check valve port of the accumulator 74 but since the accumulator ischarged to a higher pressure the accumulator check valve remains closed.The accumulator 74 supplies fluid to the line 75 and, as illustrated,causes the forward end of the cylinder 22 to be pressurized. It isassumed that at this time the piston 14* is at the end of its returnstroke, lefthand end, and, therefore, the port 76 for the associatedpilot valve 77 is closed to the port 87 communicating with the fluidmotor 22. The port 87 is in communication with the port 85, which isconnected directly to the tank 38 by means of the conduit 86. Also itwill be assumed that the piston 15 is at the end of its pumping stroketo have operated its associated pilot valve 78 to place the ports 79 and91 in communication. The fluid line 75 is also connected to the fluidline 80 in turn connected to the port 79 for the pilot valve 78. Thisarrangement for the ports of the pilot valve 78 causes fluid to betransmitted therethrough to the fluid line 71, through the ports of thereversing valve 67 to the fluid line 72 and into the right-hand end ofthe cylinder 22 of the fluid pressure motor 22 to position the piston 22adjacent the left-hand end of the cylinder 22 and thereby maintain thecontrol valve element 21 in the illustrated position. If the posi- 14tions of the pistons 14 and 15 are reversed, the positions of theirpilot valves 77 and 78 will be reversed whereby the fluid motor 22 willhave its piston 22 positioned at the opposite end of the cylinder 22 andthe control valve 21 will be in its alternate position from the oneillustrated. It should be appreciated that at this off position thefluid pressure generator 30 is not pumping because the orifice samplingline 35 is vented to the tank 38 through the check valve 36.Specifically, the orifice sampling line 35 is vented to the tank sincethe opposite end of the check valve 36 is connected to the port B of thepilot valve 40 through the port T and the conduit 45 which is directlyconnected to the tank 38.

It should be noted that an aspect of this control circuit is that at theOE position both pistons are depressurized and, therefore, there is nopressure on the concrete in the pump itself. After the pump 10 has beenin operation and it has been turned off, the pressure generator 30 isshut off and the circuit becomes depressurized, the oil flowing backinto the tank 38. At this time if there is any residual pressure in theconduit 20, it will overcome the hydraulic circuit pressure and push thepumping piston back until this pressure is relieved. The practicaladvantage of this is that if the pump is shut down for any length oftime, the concrete stored in the pump 10 will be at atmospheric pressureand there will be no tendency for the concrete to pack as in prior artconcrete pumps.

To place the concrete pump 10 in operation, the solenoid 42 associatedwith the pilot valve 40 is energized by means of the switch 44 on thecontrol panel 13. This phase of the pump operation is illustrated inFIG. 4. The energization of the solenoid 42 is effective to reverse theconnections of the pilot lines connected to the pilot valve 40.Specifically, the pressure port P is in communication with the pressureport B while the blocked port A is in communication with the tank portT. With this change in position of the ports for the pilot valve 40, theorifice sampling line 35 is no longer in direct communication with thetank 38. Tracing this fluid path it will be seen that the pressure inthe line 41 is transmitted through pilot lines 39 and 39, the ports Pand B of pilot valve 40, to line 46 to apply pilot pressure foroperating the hydraulic motor controlling the volume control valve 48.At this time this pressure path also maintains the check valve 36 closedthereby disconnecting the orifice sampling line 35 from the tank 38. Theoperation of the hydraulic motor places the ports of the valve 48 incommunication to allow fluid to pass therethrough and by means of thefluid line 49 is coupled to the reversing valve 57. The operation of thehydraulic motor for the volume control valve 48 sets the opening of thevalve to a preselected level and may be further adjusted by means of themanual control associated with this volume control valve. The orificesampling line 35 is pressurized by means of the pilot line 27 connectedto the fluid line 49, and the junction 28 on the upstream side of theclosed check valve 36. The orifice 26 controls the flow of oil to theorifice sampling port 31 of the pressure generator 30. The orifice 26 isalso employed to control the sequence of the oil flow when the pump 18is shut oif. At that time, the oil from the system is choked down by theorifice 26 to allow the oil from the generator 30 to flow to the tankfirst and then from the system. At this time the check valve 51 passesoil to the line 53 through the orifice 25 to control the small amount ofoil supplied to the chambers 14 and 15 of the pumping units 14 and 15respectively. Under these conditions the generator 30 pumps oil to thevolume control valve 48. The fluid in the line 49 is conducted to thereversing valve 57 and which valve is still in its at rest position,whereby the fluid is communicated through the ports P and A to the fluidline 58 and then into the cylinder section 14 for the pumping unit 14 topressurize the piston 14 in a pumping direction. The fluid applied tothe cylinder section 14 causes the fluid in chamber 14 to be conveyedthrough the line 94 to the chamber l of the cylinder section 15 to driveit along its return stroke. The fluid is also conveyed by means of theline 54 to the relief valve 55 which is still maintained in its normalclosed position and, therefore, is not conveyed to the tank 38. Thefluid pressure motor 22 still has fluid pressure applied thereto as inits at rest position and so the position of the control element 21 isnot changed.

The travel of the piston 15* on its return stroke forces the fluid inthe cylinder section 15 to the tank 38 through the conduit 59, the B andT ports of the reversing valve 57 and the conduit 60 directly connectedto the tank 38. It will be appreciated that the travel of the piston 15on its return stroke will produce a suction to draw concrete from thehopper 16 into the cylinder section 15. When the piston 15* reaches theend of its return stroke, the oil that is located to the right of therear piston head 15*, as illustrated, or in the chamber 15 is conveyedto the tank 38 by means of the feedback line 94 and the line 54 andthrough the relief valve 55 which is opened at this time due to theincrease in pressure. With the piston 15 reaching the end of its returnstroke it also shifts the position of the pilot valve 78. The shiftingof the pilot valve 78 disconnects the ports 79 and 91 and therebyremoves pressure from the right-hand end of the piston 22; of the fluidpressure motor 22. During this time, the piston 14- is still travelingon its forward stroke and pumping concrete out of the concrete chamber21 and through the outlet 19. This action continues until the piston 14travels against the stop 89 and reverses the position of the pilot valve77 in response thereto. The piston 14 travels to the end of its pumpingstroke and is momentarily at rest along with the piston 15*.

This position of the control circuit with the pistons 14 and 15 both atrest and at opposite ends of their strokes is illustrated in FIG. 5. Thepilot valve 77 associated with the pumping unit 14 is now positionedwhereby the ports 76 and 87 are in communication and, therefore, fluidis passed therethrough to the line 88 through the reversing valve 67 tothe cylinder 22' to the left side of the piston 22 thereby preparing themotor 22 to switch the control element 21 to its alternate position.This change in position of the pilot valve 77 also disconnects the line88 from the port 85.

When the motor 22 is pressurized to an extent to allow the piston 22 toreach its right-hand extremity, the control element 21 is switched tothe alternate position illustrated in FIG. 6. With the switch inposition of the control element 21, the concrete can then be pumped bythe pumping unit 15 through the discharge outlet 19 while the pumpingunit 14 may be charged during the return stroke of the piston 14*. Itshould be noted that during the interval that the unit 22 is beingpressurized for switching the position of the control element 21, thefour-way control valve 57 is not operated since the sequence valve 61associated therewith prevents the operation thereof. The sequence valve61 senses the pressure on the left-hand side of the piston 22 andsuificient pressure is not generated for operating the sequence valve 61until the piston 22 reaches its right-hand extremity. The only othercondition that generates sufficient pressure is when the control element21 engages a large stone or foreign object and then switches theposition of the element 21. It will be appreciated at this time thecontrol element 21 is switched and then the sequence valve 61 operatesthe reversing valve 57 as illustrated in FIG. 6. The operation of thereversing valve 57 now connects the fluid line 49 to the port P and thecommunication of this port with the port B to the fluid line 59 topressurize the left-hand end of the piston 15 to cause it to travel inits pumping stroke to move to the right. The operation of the reversingvalve 57 is also effective to connect the ports A and T together andthereby connect the line 58 to the tank 38 allowing the fluid in thecylinder section 14 to be discharged to the tank 38 with thecommencement of the piston 14 on its return stroke. The piston 14 isstarted on its return stroke due to the pressure generated by the piston15 on its pumping stroke, forcing the fluid through the line 94 into thechamber 14 and against the piston head 14 to thereby cause it to travelin the reverse direction.

With the above operation in mind, it should be noted that the switchingof the control element 21 is effected only while both pumping units 14and '15 have their pistons at rest. The operation of the control element21 at this interval minimizes the surges in the conduit and renders theconcrete pump 10 of this invention more acceptable for use by theoperator. If the control element 21 was actuated during the pumpingoperation, the surges created in the conduit 20 would be of suflicientintensity to knock down the operator or to badly shake him up. Theminimization of the surges in the conduit 20 also prevents the looseningof any forms over which the conduit may be passed due to the continuousvibration that may be set up in the conduit due to this pumping action.

With the travel of the piston 14 on its return stroke and the piston 15on its pumping stroke, the action is such that the return stroke of thepiston 14 will be completed prior to the completion of the pumpingstroke. The above sequence is repeated upon the completion of thepumping stroke of the piston 15 the control unit 22 is pressurized onceagain at its right-hand end to switch the position of the controlelement 21, and the piston 14 has fluid applied to its left-hand end toreturn it to its pumping cycle and the sequencing action repeats itself.

What is claimed is:

1. A portable pump for pumping moist, compressible materials such asplaster, concrete, mortar, and the like including:

a motor vehicle having a power unit for propelling the vehicle,

a pump for pumping said materials mounted on said motor vehicle to bemovable therewith, said pump including drive means therefor,

switchable power take-off means coupled between the vehicle power unitand the pump drive means for alternately coupling the power unit forpropelling the vehicle and for powering the drive means, said pumpfurther including pumping means coupled to be actuated by said drivemeans,

means for charging the pumping means with a material to be pumped,

a control chamber mounting a single movable control element forcontrolling the communication of the pumping means with said chargingmeans to allow the pumping means to be alternately charged anddischarged therethrough, and

control means coupled to said drive means for actuating the pumpingmeans and the control element in a preselected sequence to therebyactuate the pumping element to discharge a charged material when thecontrol element is positioned to allow communication between the pumpingunit and the control chamber.

2. In apparatus for pumping moist, compressible materials such asplaster, concrete, mortar, and the like including:

first and second piston-cylinder units reciprocable between a pumpingstroke and a return stroke,

means for charging the first and second piston-cylinder units with amoist, compressible material to be pumped,

means for defining a common material chamber having a material outletfor said piston-cylinder units,

a single control member mounted in the material chamber to control thealternate discharge of said material through the outlet by saidpiston-cylinder units,

a pilot valve individual to and constructed integrally with each of saidpiston-cylinder units,

means carried by each of said pistons and connected to the associatedpilot valve for operating same in response to the reciprocation of thepistons, and

fluid pressure control circuit means connected to said first and secondpiston-cylinder units and the control member for alternatelypressurizing said first and second piston-cylinder units and therebycausing the corresponding pilot valves to alternately operate and switchthe position of the control member when thefirst and second pistons areat opposite ends of their strokes.

3. In a fluid power control circuit having a pair of workpiston-cylinder units each having a pressure stroke and a return stroke:

a pair of pilot valves for said pair of work pistons, each work pistoncarrying a pilot rod coupled to an individual pilot valve for operatingsame at the ends of the pressure and return strokes,

a fluid pressure generator,

conduit means interconnecting said work cylinders to cause the fluidpressure applied to one of said work pistons from said generator tocause the piston to travel in a preselected direction to be applied tothe other of said work pistons to cause it to travel in a directionopposite to said preselected direction,

another work piston-cylinder unit,

conduit means interconnecting the opposite sides of said latter pistonwith one of said pilot valves for alternately applying fluid pressure tothe opposite sides of said latter mentioned piston,

a reversing valve,

conduit means connecting the reversing valve to said generator and tosaid pair of work piston-cylinder units for alternately applying thefluid pressure of said generator to said pair of work pistons,

sequence valve means connected for controlling the reversing valve, and

conduit means connected to the sequence valve means and to the oppositeends of said another work cylinder, said sequence valve means beingresponsive to a preselected fluid pressure created in said another workcylinder for operating said reversing valve.

4. In a fluid power control circuit as defined in claim 3 includingmeans for reversing the operation of said another work piston-cylinderunit.

5. In a fluid power control circuit as defined in claim 4 wherein saidreversing means comprises manually operable valve means.

6. Apparatus for pumping moist, compressible materials such as plaster,concrete, mortar, and the like comprising:

first and second piston-cylinder assemblies adapted to allow the pistonsto reciprocate between a pumping stroke and a return stroke,

means for defining a common material chamber having an outlet directlyconnected in communication with each of the first and second cylinders,

means for receiving and storing a material to be pumped and connected incommunication with each of the first and second cylinders,

a material control valve swingably mounted in the material chamber foralternately closing off the chamber outlet to one of the piston-cylinderassemblies to thereby define a free flow material path for the otherpiston-cylinder assembly through the chamber outlet,

a source of heat exchange fluid,

conduit means connected to said source and to the material receivingportions of each of the cylinder assemblies whereby the fluid in onecylinder is delivered to the other cylinder in response to the piston insaid one cylinder traveling on its return stroke,

fluid pressure generator means,

means for driving said pressure generator, and

fluid pressure control circuit means coupled to said generator means andto said first and second pistoncylinder assemblies for alternatelypressurizing said pistons on a pumping stroke and for controlling thematerial control valve to position same to provide the free flowmaterial path for the piston to be pressurized on its pumping stroke.

7. Apparatus for pumping moist, compressible materials such as plaster,concrete, mortar, and the like as defined in claim 6 wherein said, fluidpressure generator means includes a fluid pressure generator comprisinga variable volume fluid pressure generator and a fluid governorconnected thereto for maintaining a constant fluid flow in the controlcircuit, and said control circuit includes means for manuallycontrolling the volume of fluid flow in said control circuit means.

8. Apparatus for pumping moist, compressible materials such as plaster,concrete, mortar, and the like comprising;

first and second piston-cylinder assemblies adapted to allow the pistonsto reciprocate between a pumping stroke and a return stroke,

means for defining a common material chamber having an outlet directlyconnected in communication with each of the first and second cylinders,

means for receiving and storing a material to be pumped and connected incommunication with each of the first and second cylinders,

a material control valve swingably mounted in the material chamber foralternately closing off the chamber outlet to one of the piston-cylinderassemblies to thereby define a free flow material path for the otherpiston-cylinder assembly through the chamber outlet,

a source of heat exchange fluid,

conduit means connected to said source and to the ma terial receivingportions of each of the cylinder assemblies whereby the fluid in onecylinder is delivered to the other cylinder in response to the piston insaid one cylinder travelling on its return stroke,

fluid pressure generator means,

means for driving said pressure generator,

and fluid pressure control circuit means coupled to said generator meansand to said first and second pistoncylinder assemblies for alternatelypressurizing said pistons on a pumping stroke and for controlling themate-rial control valve to position same to provide the free flowmaterial path for the piston to be pressurized on its pumping stroke,each of said pistoncylinder assemblies being defined with a fluidchamber connected with said fluid pressure control circuit means toreceive fluid therefrom and including a conduit interconnecting saidchambers whereby the fluid in one of the chambers is responsive to thepressurization of the corresponding piston to cause the fluid to beconveyed to the other piston for pressurizing the other piston on itsreturn stroke.

9. Apparatus for pumping moist, compressible materials such as plaster,concrete, mortar, and the like comprising:

first and second pist-oncylinder assemblies adapted to allow the pistonsto reciprocate between a pumping stroke and a return stroke,

means for defining a common material chamber having an outlet directlyconnected in communication with each of the first and second cylinders,

means for receiving and storing a material to be pumped and connected incommunication with each of the first and second cylinders,

a material control valve swingably mounted in the material chamber foralternately closing off the chamber outlet to one of the piston-cylinderassemblies to thereby define a free flow material path for the otherpiston-cylinder assembly through the chamber outlet,

fluid pressure generator means,

means for driving said pressure generator,

and fluid pressure control circuit means coupled to said generator meansand to said first and second piston-cylinder assemblies for alternatelypressurizing said pistons on a pumping stroke and maintaining themmomentarily at rest and for changing the position of the materialcontrol valve when both pistons are at rest to position same to providethe free flow material path for the piston to be pressurized on itspumping stroke, said control circuit comprising a piston-cylinderassembly for controlling the position of the material control valve,means for sensing the pressure on opposite sides of said last mentionedpiston-cylinder assembly, a four-way reversing valve connected to saidgenerator means and to said sensing means for operating same when thepressure in said last mentioned cylinder is at a preselected levelduring an interval both pistons are momentarily at rest to connect thefirst and second piston-cylinder assemblies to the generator means forreversing the position of the first and second pistons.

10. Apparatus for pumping moist, compressible materials such as plaster,concrete, mortar, and the like as defined in claim 9 wherein saidcontrol circuit means includes a manually operated reversing valveconnected in circuit with the material control valve piston-cylinder forselectively reversing the action thereof and thereby the pumping action.

11. In apparatus for pumping moist, compressible materials such asplaster, concrete, mortar, and the like, including: first and secondpumping units, means for charging the first and second pumping unitswith said materials, a common discharge passage for said pumping units,hydraulic drive means for alternately operating said first and secondpumping units in a timed relationship whereby both units are momentarilyat rest, a discharge control member mounted in the discharge passage tocontrol the alternate charging and discharging of said materials throughthe passage by said pumping units, a discharge conduit connected to saiddischarge passage, hydraulic control means connected to said controlmember for changing the discharge position of said control member duringthe interval the pumping units are at rest, and manual means forreversing the pumping action of said pumping units to cause the pumpedmaterial to be pumped back through the discharge conduit and into thecharging means.

12. In apparatus for pumping moist, compressible materials such asplaster, concrete, mortar, and the like, including: first and secondpumping units, means for charging the first and second pumping unitswith said materials, a common discharge passage for said pumping units,hydraulic drive means tor alternately operating said first and secondpumping units in a timed relationship whereby both units are momentarilyat rest, a discharge control member mounted in the discharge passage tocontrol the alternate charging and discharging of said materials throughthe passage by said pumping units, a discharge conduit connected to saiddischarge passage, hydraulic control means connected to said controlmemher for changing the discharge position of said control member duringthe interval the pumping units are at rest, manual means for reversingthe pumping action of said pumping units to cause the pumped material tobe pumped back through the discharge conduit and into the chargingmeans, and a motor vehicle mounting said pumping apparatus to be movabletherewith, said drive means being adapted to be powered from the powerunit of the motor vehicle.

13. In apparatus for pumping moist, compressible materials such asplaster, concrete, mortar, and the like, including: first and secondpumping units, means for charging the first and second pumping unitswith said materials, a common charging and discharging passage for saidpumping units, hydraulic drive means for alternately operating saidfirst and second pumping units in a timed relationship whereby bothunits are momentarily at rest, a rotatable discharge control membermounted in the discharge passage to control the substantiallysimultaneous charging and discharging of said materials into and out ofthe passage by allowing alternate charging and discharging of saidmaterials through the passage by said pumping units, hydraulic controlmeans connected to said control member for rotating said control memberduring the interval the pumping units are momentarily at rest, and meansfor reversing the pumping action of said pumping units to cause thepumped material to be pumped back into the charging means.

14. In apparatus for pumping moist, compressible materials such asplaster, concrete, mortar, and the like including: first and secondpumping units, means for charging the first and second pumping unitswith said materials, an enclosed material chamber having a materialoutlet in communication with said pumping units and said charging means,a plate-like control member swingably mounted in the chamber tosub-divide the chamber for alternately allowing the sub-divided portionsto function with said pumping units as a means to charge the materialtherein and to discharge the material therefrom, the control memberbeing constructed, defined and arranged relative to the chamber toisolate the portion of the chamber discharging material fromcommunication with the charging means but in communication with saidchamber material outlet and to maintain the other portion incommunication with the charging means while isolating it from saidchamber material outlet, and automatic means for operat ing said pumpingunits and for changing the position of said control member in apreselected timed relationship.

15. In apparatus as defined in claim 14 including liquid means forsimultaneously cooling and lubricating the pumping units.

16. In apparatus as defined in claim 14 wherein the pumping units arepiston-cylinder units and a liquid is stored in at least a portion ofthe cylinders that the associated work piston head travels in forsimultaneously cooling and lubricating the piston head and thereby thematerial being operated on.

17. In apparatus as defined in claim 16 wherein the liquid is water orthe like.

18. In apparatus as defined in claim 14 wherein said operating means iscontrollable and includes means for remotely controlling said operatingmeans.

19. In apparatus as defined in claim 14 including means for reversingthe operation of the control member to thereby reverse the pumpingaction on the material.

20. -In apparatus as defined in claim 19 wherein said means is manuallycontrollable.

2 1. In apparatus as defined in claim 14 wherein said operating meansincludes automatic control means for operating said pumping units in atimed relationship whereby both units are momentarily at rest and torotate the control member during the interval the pumping units are atrest.

22. In apparatus as defined in claim 21 wherein said operating means ishydraulic operating means.

23. In apparatus for pumping moist, compressible materials such asplaster, concrete, mortar, and the like comprising: first and secondpumping units, means for charging the first and second pumping unitswith said materials, a totally enclosed material chamber having amaterial outlet arranged in alignment with each of the pumping units andthe charging means and constructed and defined to allow the material toflow freely to and from the chamber, the pumping units and the chargingmeans, a solid control member rotatably mounted in the chamber to dividethe chamber in a fashion for alternately allowing the portions on theopposite sides of the control member to function for charging anddischarging material therethrough substantially simultaneously inaccordance with the position thereof, liquid storage means mounted incommunication with each of said pumping units for cooling andlubricating each of the pumping units, and hydraulic means for operatingsaid pumping units in a preselected timed relationship whereby each ofthe pumping units are momentarily at rest and for operating said controlmember during the interval said pumping units are both at rest.

24. In apparatus of the type defined in claim 23 including manual meansfor reversing the pumping action to cause material to be pumped backinto the charging means.

25. In apparatus of the type defined in claim 24 including means forremotely controlling the operation and speed of the pump.

26. A fluid power control circuit comprising a pair of workpiston-cylinder units each including a reciprocating piston having apressure stroke and a return stroke, means for maintaining a constantfluid flow, another work pistoncylinder unit, conduit meansinterconnecting said work cylinders and said means to cause the fluidapplied to one of said pair of work pistons from said fluid means tocause the piston to travel in a preselected direction to be applied tothe other of said pair of work pistons to cause it to travel in adirection opposite to said preselected direction, valve means forcontrolling the flow of fluid to the opposite sides of said anotherpiston and adapted to be operated in response to the completion of thestrokes of said piston-cylinder units, conduit means interconnecting theopposite sides of said another piston with said valve means foralternately applying fluid to the opposite sides of said latter pistonin response to the completion of the strokes of both of said firstmentioned piston-cylinders and thereby operate the latter mentionedpiston-cylinder unit when said other pistons are momentarily at rest,re-

versing valve means, sequencing valve means connected for controllingthe reversing valve means, and conduit means for connecting the sequencevalve means to said another Work cylinder.

27. A fluid power control circuit comprising a pair of fluid pressureresponsive pumping units, means for applying fluid under pressure tosaid units for alternately operating them in a pumping stroke and areturn stroke, another pumping unit normally arranged to be in anonworking condition during the operation of the pair of pumping units,valve means including reversing valve means connected to said pumpingunits for alternately applying fluid thereto for causing them to bealternately in a pumping and return stroke and to reverse their strokesafter a preselected interval they are both at rest and to operate saidanother pumping unit during said preselected interval, and sequencingvalve means operable in response to the operation of said anotherpumping unit for actuating said reversing valve means to eflect saidsequencing.

28. A fluid power control circuit as defined in claim 27 includingmanual means for reversing the operation of said another pumping unit.

References Cited by the Examiner UNITED STATES PATENTS 706,979 8/1902Martin 230-212 X 2,366,417 1/ 1945 MacMillan 103--49 X 2,462,588 2/ 1949Wondra 230-38 2,620,965 12/1952 Miller 230--38 2,690,715 10/1954 Popel0349 2,998,781 9/1961 Triebel l0349 3,068,806 12/1962 Sherrod 1(l31533,128,711 4/1964 Voigt et al 103-45 3,146,721 9/1964 Schwing 103493,181,469 5/1965 Schumann 10'349 ROBERT M. WALKER, Primary Examiner.

1. A PORTABLE PUMP FOR PUMPING MOIST, COMPRESSIBLE MATERIALS SUCH ASPLASTER, CONCRETE, MORTAR, AND THE LIKE INCLUDING: A MOTOR VEHICLEHAVING A POWER UNIT FOR PROPELLING THE VEHICLE, A PUMP FOR PUMPING SAIDMATERIALS MOUNTED ON SAID MOTOR VEHICLE TO BE MOVABLE THEREWITH, SAIDPUMP INCLUDING DRIVE MEANS THEREFOR, SWITCHABLE POWER TAKE-OFF MEANSCOUPLED BETWEEN THE VEHICLE POWER UNIT AND THE PUMP DRIVE MEANS FORALTERNATELY COUPLING THE POWER UNIT FOR PROPELLING THE VEHICLE AND FORPOWERING THE DRIVE MEANS, SAID PUMP FURTHER INCLUDING PUMPING MEANSCOUPLED TO BE ACTUATED BY SAID DRIVE MEANS, MEANS FOR CHARGING THEPUMPING MEANS WITH A MATERIAL TO BE PUMPED, A CONTROL CHAMBER MOUNTING ASINGLE MOVABLE CONTROL ELEMENT FOR CONTROLLING THE COMMUNICATION OF THEPUMPING MEANS WITH SAID CHARGING MEANS TO ALLOW THE PUMPING MEANS TO BEALTERNATELY CHARGED AND DISCHARGED THERETHROUGH, AND CONTROL MEANSCOUPLED TO SAID DRIVE MEANS FOR ACTUACTING THE PUMPING MEANS AND THECONTROL ELEMENT IN A PRESELECTED SEQUENCE TO THEREBY ACTUATE THE PUMPINGELEMENT TO DISCHARGE A CHARGED MATERIAL WHEN THE CONTROL ELEMENT ISPOSITIONED TO ALLOW COMMUNICATION BETWEEN THE PUMPING UNIT AND THECONTROL CHAMBER.